Update HitTestDisplayItem comment.

As of refs/heads/master@{#608185}, it is no longer a DrawingDisplayItem.

Change-Id: If25c6d41fdc15dd3bf3b21360eb3306105a1c75e
Reviewed-on: https://chromium-review.googlesource.com/c/1355322
Commit-Queue: Xianzhu Wang <wangxianzhu@chromium.org>
Reviewed-by: Xianzhu Wang <wangxianzhu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#612240}

third_party/blink/renderer/platform/graphics/paint/hit_test_display_item.h

@@ -11,7 +11,7 @@
 
 namespace blink {
 
-// A special DrawingDisplayItem containing hit test data.
+// A special DisplayItem containing hit test data.
 class PLATFORM_EXPORT HitTestDisplayItem final : public DisplayItem {
  public:
   HitTestDisplayItem(const DisplayItemClient& client,